1. Field of the Invention
The present invention relates to an information display apparatus for forming a liquid crystal display surface by a liquid crystal display device. More particularly, it relates to a portable information terminal apparatus that may be applied with advantage to a portable information terminal unit and a lock control system for locking the mounting of the portable information terminal unit to a cradle. This application claims priority of Japanese Patent Application No. 2002-027200, filed on Feb. 4, 2002, the entirety of which is incorporated by reference herein.
2. Description of Related Art
Recently, an information terminal unit convenient for transportation, such as a so-called mobile computer or PDA (Personal Digital Assistant), referred to below as a portable information terminal unit, is being developed extensively.
These portable information terminal units use a liquid crystal display from the perspective of achieving light weight and thin thickness, as shown in FIG. 1. A portable information terminal unit 8 demonstrates the necessary information for the user through a display. This display uses a liquid crystal display device as an optical modulation element and displays the text or a picture by reflecting the external incident light.
The user executes necessary inputting operations through the liquid crystal display responsive to the text or the picture demonstrated on the liquid crystal display. Thus, the liquid crystal display is designed as a pressure-sensitive display panel which enables desired input on pressure application with a finger tip or with a pen-type actuating rod.
FIG. 2 shows the back surface of a conventional portable information terminal unit 8, and a cradle 9 on which is mounted the portable information terminal unit 8.
On the back surface of the portable information terminal unit 8 is mounted a cradle connection terminal 81. This cradle connection terminal 81 is an interface for inputting/outputting data to or from the cradle 9.
This cradle 9 is a stand type docking station having a center recess in which to mount the portable information terminal unit 8. The cradle 9 includes a terminal unit connection terminal 91 for mounting the cradle connection terminal 81 and a USB cable 92 for connecting electronic equipment, such as a personal computer, or a power supply unit. That is, the portable information terminal unit 8 is able to co-own data with the electronic equipment on mounting the portable information terminal unit on the cradle 9. The portable information terminal unit 8 also is supplied with power over a USB cable 92 from, e.g., a charging power supply of an electronic equipment or a battery on setting the portable information terminal unit 8 on the cradle 9.
By mounting the portable information terminal unit 8 on the cradle 9 as shown in FIG. 3, the user is able to view the liquid crystal display on a table or in a motor vehicle without manually holding the portable information terminal unit 8.
Meanwhile, since the portable information terminal unit 8 is lightweight and small-sized for enhancing the portability, it tends to be disengaged from the cradle 9 on which it is set, even under the slightest oscillations. Moreover, the portable information terminal unit 8 can be taken out readily, so that it is prone to be stolen, and hence may be insufficient in security.
Heretofore, in order to secure the portable information terminal unit 8 on the cradle 9 or to prevent burglary, a lock mechanism was provided for locking the mounting between the portable information terminal unit 8 and the cradle 9. With this lock mechanism, a key is inserted into a burglary-proofing device mounted to the portable information terminal unit 8 and/or to the cradle 9 or a password set from user to user is entered to achieve the lock.
However, if the burglary-proofing device, for example, is to be provided in the above-described lock mechanism, the user has to carry the key at all times. Moreover, once locked, the user has to insert the key into the burglary-proofing device each time he/she is to carry the portable information terminal unit in order to unlock the terminal unit, thus increasing the load on the part of the user.
Additionally, since Internet services and software products nowadays require various different passwords, it is cumbersome for the user to set and learn by heart a password composed of a number of digits in order to prevent burglary of the portable information terminal unit 8.